Posts Tagged ‘electronic art’

Fun with LED arrays

24 May 2020

I have been playing around with simple ways to make patterns on LED arrays.

Here’s one demonstration of how the same numeric pattern looks on a regular “square” array (cartesian coordinates) and on a circular or radial array (polar coordinates, you could say).

The circular array is quite suited to my work, because I am working with repetitive patterns and polar coordinates are usually used for things that repeat, like rotating planets or the sine wave that comes out of your wall socket.

Here we have a demonstration first of what x=y (cartesian) looks like on square and circular arrays. On the square array it’s just a diagonal line from the lower left corner to the upper right corner. On the circular array it’s a spiral.

When I flip the switch to take the x and y signals out of synchronization, where (in this case) x and y are different by about a ratio of 2 to 3, we get a slowly moving slanted line on the square array and a pulsing pattern – basically a set of spirals – on the circular array. So this condition looks more interesting. Many patterns are possible using this sort of system, and this is one thing I’m working on while stuck at home.

Circular arrays

Circular arrays that use base-2 numbers (8 or 16 for instance) are, as far as I can tell, non-existent as manufactured items. That means I have to make them myself. Here’s what my recently-constructed 8-by-8 array looks like in the back:

circular array rear view

Without going into laborious detail, you can see this took a bit of work.

I continue to look for pre-fab boards with circular patterns, but so far have only found ones used for clocks (12 points in the circle, or some multiple of 12). Digital ICs (old school CMOS) almost all use binary counting. As the standard IC has 16 pins, the most places you can pull out of one is 8. The binary number comes in as 3 bits (up to 8 places) or 4 bits (up to 16 places) and can be resolved to 8 places with one IC, or 16 with two, etc.

I may learn how to design my own boards for this purpose. We’ll see about that.

Tidbits

26 April 2020

…consisting of somewhat random notes.

The Arboretum

It was warm this weekend! And when it gets hot – which means I get hotter on my ride home – I usually stop at the arboretum (UC Sac State) along the way.

butterfly bush flowers

Here is the butterfly bush mentioned on the marker above. Exotic!

And an iris.

iris

Nearby were some calla lilies.

calla

This is quite a peaceful place. And popular as a way to take in a short walk.

There were a lot of people out Saturday. The regular bike racers, plus a ton of families with kids.

The weather, predicted to be partly cloudy, turned out mostly sunny, and I got burned.

eArt Projects

At home I have been working – almost feverishly – on putting together some systems that will allow me to continue to develop more electronic art.

I worked a lot on an oscillator made from an old IC known as “XR2206.” This IC is considered very outdated, yet it continues to have popularity among hobbyists and can still be obtained from electronics surplus stores. One wonders, though, why these parts are surplus. Could it be they were rejected by the original manufacturers due to being out-of-specification?

What I know about this IC is that it has been hard for me to work with in that it does not deliver the full functionality it was specified for. In theory, you can get a 2000:1 frequency range out of this part, but this is difficult to achieve because at higher current levels it begins to go unstable or stop oscillating.

Still it is a great way to get a sine wave for testing purposes with just the turn of one knob. And that’s all I needed it for.

XR2206 oscillator

This is an important part of my “analog” rack. This rack is for developing different ways to process sound and turn it into signals that can control light (LED) displays.

Below the oscillator is an open section where boards can be inserted for testing. That part isn’t finished yet.

analog rack

The whole thing looks like this right now.

The mounting rails with all the little screw holes in them are taken from the “eurorack” system. This system was developed as a metric standard that imitates the old U.S. standard 19-inch wide equipment racks. This rack size has continued to be popular for computer equipment and for professional audio equipment. The eurorack has become the default standard for modern modular equipment, especially analog (old-school) synthesizers. The “new breed” of “analog” synths can be computer-aided, which helps to overcome some of their old problems with tuning stability, amount of space required, and similar issues.

I note that vinyl as a recording medium is also back in vogue. Some people really think it sounds better.

I use these racks for projects that need to be modular – built in functional sections. They are a great substitute for older rack equipment which tends to be way too deep for this sort of application. Lots of professional synth modules are less than 1 inch deep behind the panel! My racks are about 4 inches deep. That was not quite deep enough, however, for the power supply module I found (at a very good price) so I had to make a hole in its panel so it could stick out 1/2 an inch in the front. That meant putting a thick plastic cover over it so it would be electrically safe.

I also have an analog meter in this rack, as I sometimes want to see the slower changes in a signal, and digital meters aren’t good for that.

digital rack

My digital rack is very similar, except it all works on 5 volts. Its purpose is to help me design digital pattern generators that will respond (usually) to one or more analog signals taken from the environment.

Here is another open section where boards may be inserted to try them out. That still needs more work.

Deliveries

I wanted a better webcam in case I had reason to use one over this period or later. So I ordered one and asked for it to be delivered by the second business day (Fedex). The driver, however, could not get into my building because the managers have not been unlocking the door when they’re in the office, like they usually do. For some reason he didn’t think to (or couldn’t) call me so I could let him in, so it’s the third business day and the camera remained undelivered.

I decided to go out to the Fedex facility and pick it up. It wasn’t hard, though it took about two hours by bus. Right now the bus drivers have to wear masks and all the passengers have to enter and exit via the back door (unless they are wheelchair types). Most people are taking it pretty well, but I think it’s crazy.

My electronics parts orders have been coming through pretty well, though. The USPS has no problem delivering the mail, and orders from California only take two days to get here, so that’s working for me.

Is the way out the way through?

This is an old saying used in Scientology, but actually broadly applicable. It means that if you have something hanging around that’s bothering you, it’s only there because you didn’t confront it well enough the first time you ran into it. The only way to get rid of it is to confront it more thoroughly.

While some doctors, including that Fauci dude, remain almost studiously ambivalent about this particular disease, the fact is that we wouldn’t be alive on Earth today if we didn’t have some natural way to build up immunity against all the pathogens floating around in the environment. And so, while it takes its toll on us to one degree or another, we will build up our immunity to this one, the next one, and a few more after that (I hope).

The doctors who do talk about immunity and the immune system as the way through this thing are oddly ignored by some of the others who want drugs or a vaccine to handle it. This has led some of them to wonder out loud if the medical establishment has some “agenda” it’s trying to push forward (to make more money and gain more control), and from all I’ve heard and read, this is quite possible.

What I know for sure is: This disease needs to run its course, and people need to get back to what they were doing to earn money and make things go right. You can’t put the world on hold forever without killing it. Is that what those doctors want?

Here’s another photo of flowers. They don’t seem to be aware that there’s anything wrong.

yellow flowers

My Latest Big Project

16 April 2020
open side of pattern generator and serializer

I have been working on my latest project for about a week straight now. It’s finally in a usable form.

This project has several purposes behind it. First, I needed a pattern generator to test LED arrays that would output very ordinary patterns, nothing fancy, just so I could tell if the display was working. Second, I needed the output to be serialized to simplify connection of the display to the signal source. Third, I wanted to use as many old boards as I could, rather than junk them.

This project incorporates about a dozen old boards that were taken out of “dead” projects and gathering dust on my bench. They all had to be re-worked for this project. It also incorporates some older pattern generation circuits as a way of preserving a technology I have not been using recently.

Here is another shot of the project:

new project showing front panel

Here we can see the front panel which has four main knobs, DIN connectors for the serial signal output, and some other controls.

Added Control Systems

This was an ambitious project for me basically because of the additional front panel controls that I would not put on equipment unless it was being used to test other equipment.

Besides the four voltage-controlled oscillators (VCOs) that have been fairly standard in my eArt projects, there is a pattern selector that is implemented by a rotating “click” knob that I got off an old mobile radio. This gives me about 64 different possible combinations using just one knob.

The other thing I wanted to implement was the ability to isolate just one section of a pattern and show only that on the display. For this I used an old 4-bit binary rotary switch that I had laying around (making 16 possible choices) and some comparison logic using the infamous “XOR” (exclusive OR) gate, also known as a binary adder. This gate, basically, has one output (“0”) if the two inputs match and another output (“1”) if the two inputs are different. AND the outputs together (after inverting them), and you see if two binary numbers match for as many bits as you need or want.

As a geeky aside, I made use of the fact that binary AND and OR are complementary functions. Thus, you can accomplish a binary AND on the outputs of the XOR gates without inverting them first (to make a match = “1” instead of “0”) using an OR gate, which then gives you a “0” output only when there is a match (when all inputs are “0”). Invert that, and you get a “1” for a match. In my case I needed the “0” to show a match!

I also wanted to choose between the “legacy” patterns that I built into this project and the “simple” patterns used for test purposes. For this I used a 4-bit selector IC. One can make a “tree” of these ICs and select from as many different inputs as one wants.

I don’t build these sort of control circuits that much, so I had to do a bit of head-scratching along the way.

My bench and a few closeups

The project on my work bench

I don’t photograph my bench that often because it looks so messy. But here we see my current setup with the project and one of my displays on it.

To the left is a small oscilloscope and you can see its two test leads hanging down from little hooks. In the center is one of my numerous parts cabinets. Behind the project is a work light and a soldering iron. Above the light is a digital meter I bought used (highly recommended for an electronics bench) and above that a rack chassis full of power supplies. The supply with the panel lit up is the one I use the most.

my bench power supply

It produces four different voltages, 5, 7.5, 9 and 12. I use 5 volts the most. The panel had room for two meters (eBay specials!) so I can monitor more than one output at a time if I need to. Here it shows my five volt connection switched on and drawing 38 milliamps. With CMOS logic, most of the circuitry draws close to zero power. Most of this current draw is from the oscillators.

The 12 volt meter shows 18 mA current draw. This is from the panel meters themselves. It was easier to power them from one of the four supplies, rather than adding another just for them.

pattern generator set up in demonstration area

Here we see the pattern generator installed in its case and running the same display. This is in the “demonstration” area of my room.

closeup of the panel

There is room for another panel section above the one I used. You can also see the binary rotary switch set to “A” which is ten in hexadecimal.

8 spirals display

Here is “8 spirals,” one of my more colorful displays. All the lights should be lit in this pattern, but you can see that there are two lights having problems.

Electronic Art – Three Circles

29 March 2020

I thought I’d try to show the latest revision of one of my art projects in video form. At first I tried an old webcam (LifeCam VX-3000) with bad results. Then I decided to use my digital camera. With the current memory card it can record up to 5 minutes of video in Quick Time format. I added a pan and zoom effect using Windows Movie Maker (available in Win 8, not 10).

Latest project updates

In this rare view of some of my gear (doesn’t it look atrocious?) we see a military-green piece of equipment in the middle serving as a signal source to the display module (upper left). The gray cable carries the signal, a serial signal needing only 3 wires plus ground, with a fifth wire providing power to the display. The pattern generator creates an 7-or-8-bit-wide pattern which is monitored on its own local display, then serialized in the top part and sent through the five-wire cable. The pattern generator can also encode the 3 signals into 2 signals and send them out using four wires plus ground. This allows for very long cables.

I want to make this the standard for how my displays work, and this is the first time I have all the parts in the chain up and running.

The display looks cooler than the halting, grainy video conveys. And that’s only one set pattern. The possible variations are infinite. Now that I have all the basic pieces in place, I will be converting more of my older displays to work with a serial cable, and finding better ways to take videos of them so you can see how they really look.

Here’s another video I took after building some more pattern-making equipment.

The Mergansers return!

20 December 2019

The Folsom Mergansers were first mentioned here: https://lecox.wordpress.com/2019/03/03/i-sight-a-special-bird/

This is the first time I’ve been able to photograph one myself. As you can see, they are a striking bird (technically, this is the Hooded Merganser).

My understanding is that they migrate down from northern areas to winter in warmer areas like the California Central Valley.

Other returnings

Life Force Tree electronic art.

I have revived two of my older electronic art (eArt) projects. Above, the “Life Force Tree,” comprised of eight concentric circles of lights, each ring with one more light in it than the next inner one. That means 3-4-5-6-7-8-9 and 10 lights. I have switched this to be fed from a shift register, which needs only 3 signals to run 52 lights. This makes having a remote controller a lot easier. I added a pretty nice wood frame to make it look a little more elegant.

My other project uses rewired Christmas lights. They are in a 6 by 10 array, but my current electronics only controls a 6 by 8 array. Again, a shift register scheme has been used to reduce the number of wires needed to control all these lights. I am just beginning to work on a remote control box for this project. This is where the real creative work comes in, as the pattern that is generated (and constantly moves and changes) is a result of the interaction between the signals generated by the controller and those used to operate the display itself.

Electronic art using Christmas lights.

Happy holidays!

Day of the Dead

27 October 2019

We are creeping up on Halloween, so why not work with that theme this week?

The significance and timing (end October) of the observance itself has been a Christian tradition for so long, that the possibility that is was originally a non-Christian observance is now in doubt, even though a traditional Gaelic festival was observed at the same time of year.

Dia de Muertos

In Mexico, the Dia de Muertos tradition definitely began as an observance connected to Aztec tradition and beliefs. Everyone in Mexico knows this. However, it was not traditionally observed at this time of year, but rather at the beginning of summer. When the Spaniards came, this eventually got shifted so that this observance coincided with what we know as Halloween.

In most earlier religions or spiritual systems, the spirit was believed to survive death in some manner. Most religions believe that the spirit “goes somewhere,” but can return to “visit” for various reasons. Though there may have been some societal need fulfilled by this belief system, it is also possible that these ideas came from actual experience, as our best data indicates that the spirit does indeed “leave” and then “come back.”

dia_de_los_muertos-old_sac-20181103-80

In the case of the Mexican tradition, it was taught that this day, or these days (two or three special days may be observed) are somehow set aside for the spirits of those you loved to come back and visit. Little (or not so little) alters of offerings would be set up for those who we hoped would come visit, to make them feel welcome and more comfortable. Note the modern Californian add-ins to this alter display from last year’s celebration in Old Town.

dia_de_los_muertos-old_sac-20181103-78

The circular arrangement of little white bags and oranges (I think) depicted above is not understood by me, but was certainly quite noticeable.

The Devil’s Motorcycle

halloween-black-motorcycle-20191026-20

I had to find some excuse to include an image of this impressive bike I found parked outside Folsom Winco.

In the fantastical comedy film Raising Arizona, something close to a real devil rides such a machine. I have seen several films that have used the motorcycle as a sort of symbol of approaching danger.

Spooky Butterfly

halloween-buckeye-butterfly-20191026-30

This insect is called the “Buckeye,” and the patterns on its wings are called “eye spots.”

Kinda spooky!

Death in Popular Lore

It is surprisingly difficult for most of us to remember what happens when we die. This memory loss has advantages both for us and for the managers trying (never very successfully) to keep us all under control. For us, it means we can end a lifetime by shedding all responsibilities for what we did or didn’t do during it, and “start afresh” every time we get born. For the managers it means we are less likely to realize that we are immortal beings and should hold in contempt any effort to control us by threatening us via our bodies (with torture, death and the like).

As a result, our ideas about what it means to die and “come back” are a bit off base, kooky, and unrealistic. Some think of the departed rising from their graves as animated skeletons. Others think of returning spirits as a bit demonic, tormenting us with swirls of smoke or dust in the shape of bodies and playing tricks on us that are frightening. Some think that they can leave something around to remind you of them.

We could see “trick or treat” I suppose as sort of a dramatization of our attempts to appease the departed so that they won’t continue to bother us. That we in the U.S. use little children to play the role of the returned ones is ironic.

As a part of this whole tradition, those of us who have houses and can afford the time and expense will “dress up” their front yards in keeping with the “spirit” of the season.

halloween-4900L-20191026-32

This could be seen as a playful and creative pastime, I suppose. However, the scariest front yards I remember as a kid were the ones that were actually small forests that you had to walk through (or creep through) to get to the house. Spooky!

halloween-4724L-20191026-33

The bright orange pumpkin is a great way to decorate the yard as winter begins to turn it brown. Of course, in Sacramento, most of the yards never do actually turn brown…

halloween-1216-20191026-34

I can only imagine this to be the house of a doctor. How else would he have access to so many (classroom) skeletons?

The Vulture

A lurking, dark and nasty-looking bird is a great symbol for spookiness. In Poe’s famous poem, it was The Raven. Well, I didn’t find one of those, but I did find this vulture.

halloween-vulture-20191026-25

The dead tree he (or she) is sitting on really adds a dramatic touch, doesn’t it? But I thought I’d try to push it a little further with the color adjustments available in my image editor.

halloween-vulture-dark-20191026-25

Now we have more of a night time scene, with the bird in silhouette on a moonlit branch.

My Halloween Project

I always try to squeeze in a project at Halloween time. Though I didn’t have as many LEDs as I really wanted, I’m going for an animated electronic jack-o-lantern.

halloween-eArt-20191026-38

Hope I finish it in time!

 

 

 

 

Untitled

14 September 2019

That’s what a painter calls a painting when he can’t figure out what it’s about, right? Or just doesn’t know what it’s about?

This is a short post touching on a diverse, perhaps unrelated, set of topics.

Miniature Steam Trains

steam-train-model-ARP-20190907-68

I pass by the park pictured above every Saturday on my way home from Folsom. I have noticed the miniature train tracks many times. But last week – I believe as a special event – the miniature train enthusiasts who use these tracks brought out some of their trains and rode them around. The group is called the Sacramento Valley Live Steamers Railroad Museum. It is a non-profit hobbyist group and they create all the trains and tracks, as well as maintain them.

Electronics

I wanted a sound-sensitive signal for my “Dial” series of electronic art pieces. Last week I started building a board that would give me such a signal. I have all the basic circuitry in place now. I seldom photograph my “development environment” so thought I would this time. The two odd things sticking out of the board are oscilloscope probes. I really needed an oscilloscope for this project, as timing is very important.

eArt-developing-a-board-20190908

Wildflowers and Acorns

While most plants in this area are dying back from the lasting heat of late summer, a few hardy composites (a huge family of plants including sunflower, goldenrod, daisies, dandelions, etc.) continue to flower or are just now beginning to flower. The first is a “tarweed.” I have shown it before. I am amazed that it continues to bloom, and in what seems to be a very dry field.

tarweed-ARP-20190907-59

The next is another flower I have shown before. For some reason I have had difficulty getting my camera to focus on this flower in closeup mode. Every week it’s still there, and I try taking a few more photos of it.

yellow-flower-ARP-upper-trail-20190831-034

This next one is just starting to bloom in some places along the trail. This photograph was taken at the site of a creek bed restoration project. These plants may get a little extra water in the summer. They are certainly growing vigorously at this site.

compositae-ARP-20190914-110

Evergreen oaks dominate the forests and fields in this area, and they are producing acorns. I believe this is a blue oak. It looks similar to a live oak, but with less glossy leaves. These long acorns are sweeter than those produced by red oaks or black oaks. They were a huge food resource for the natives of the past, but very few people use them now. Acorn flour is commercially available, but very expensive. That may change some day.

blue_oak-acorn-ARP-20190907-45

Sustainability versus the 2045 initiative

One way to “beat” climate change would be to bypass the need for biology on this planet. As batty as that may seem, there is a team of people – it seems to be a joint Russian and American project – working on doing just that.

I thought I might revisit this issue to see if anyone is still taking it seriously. This could be one reason that some sectors of society just don’t seem to be playing the sustainability game; they think they have another answer.

The problem is that it is actually a possible answer, but these guys don’t have it right. As long as they continue to not have it right, it’s basically just a con game to give a bunch of irresponsible researchers and engineers something to do while the planet falls apart around them.

In the West Ray Kurzweil is the project’s main spokesperson. And Oh Shit: He has been Google’s “director of engineering” since 2012. In Russia, Dmitry Itskov is the founder and key proponent of the movement. He has made billions in Russia with his media businesses. As of 2013 they had the Dalai Lama on board. But they have received no press since 2016, which was a thumbs down from the BBC. It is also reported that the late Jeffrey Epstein, accused of numerous sex crimes, also believed in transhumanism. That wasn’t exactly good press, either! Perhaps these boys have retreated to a safer position behind the secrecy which their non-governmental status affords them.

And as I said, right now they are no more than silver-tongued con men. The human personality already is immortal. Only the body is not. The body is currently a biological machine. It could be re-designed to be a non-biological machine. I suppose some of us, if not eventually all of us, could learn to live in a non-biological machine instead of a biological one. But it seems to me that before any of that happens, we need to get the basics of life correctly understood, and we need to rehabilitate our ability to be ethical. Machines could learn to fight and “kill” each other just like humans have. Maybe it would be fun. However, that’s not how we currently experience war and terrorism. I think we first need to learn how to live properly with the bodies we have before trying to move into new ones. And we need to learn to take care of planets, too.

However, given the data above, there may be something to my idea that some sector on this planet has an “alternative” to sustainability that they think will pull them through.

 

 

Dial Two

4 May 2019

This is my third project in the “dial” series. See Dial One here.

With this project I wanted to try out a few design options, and I concentrated on those.

Though it is still far from a thing of beauty, the more minimal enclosure, featuring primarily the dial itself, was one thing I wanted to try. There was plenty of room for the electronics, and a nice big dial, but putting the power supply in the box seemed not possible. This is not necessarily a big problem, as the system also requires a sensor, or signal source box, and this could supply the power.

dial_two-20190430-88-cropped

The dial itself is irritatingly green, but in a more finished version, that board could be painted black. For the “featured” photo I adjusted the color balance to fade the green down.

16 steps

The other feature I wanted to try was a 16-step dial.

For this design I abandoned the idea of scanning the dial, which meant inventing a significantly different way to get the dial pattern to move around. Each step on the dial is on or off depending on a latch which stores that value for one cycle of 16 steps. Each latch gets its data from a common signal line, but the time when the data is transferred is different for each latch. In that way, the signal – which carries the pattern – can be time-delayed relative to the scanning pulses, thus updating the position of the “pointer” for every 16-step cycle.

Lights and Colors

To keep things simple, I used one circle of white LEDs. But this does not seem very aesthetically pleasing. I need to find colors that will work better. There is also no fading built into this design; the lights are either full on or full off. More control over light intensity seems desirable here. My next design will address these issues.

dial_two-20190430-98-slightly-lightened

This photo was made under very low-light conditions, then brightened slightly with digital manipulation. But this only slowed down the camera enough to show three lights on at once. I am considering making videos of my projects. That would give you a better idea of how they look “live.”

Dial One

14 March 2019

“Dial One” is the first piece of electronic equipment I have made that I am officially considering a piece of art, and am offering for sale as such.

dial_one-darker-20190314

It was conceived while I was on the Purification Rundown and completed in this form just yesterday. Like most art concepts – and most electronic equipment – there are many possible ways to turn the concept into reality, and many possible “variations on the theme,” or parts of the design that could be made differently. This is the first working prototype of this concept – a dial. On the circular screen, a pattern of lights rotates as an input signal varies between zero and five volts.

Dial One has all the basic features I imagined for this type of piece. With 4 knobs, the user can vary the pattern of lights. There is a sliding control for testing the effect, and a connector for an external sensor which would provide some varying signal (such as sound level or distance of nearest object). The display can be made totally dark or rather bright.

This particular prototype is housed in a black aluminum enclosure originally made for a vacuum tube voltmeter. The display features white, red and orange LEDs. Power is supplied through a standard computer-type power cord inserted in the rear.

The circuitry is all hard-wired – no programmed elements. This was the original concept for this piece, so I kept it that way. In fact, I could not immediately think of an easy way to achieve this same effect using a micro-controller. I plan to return to this concept again before too long and explore some different ways to implement it.

Patterns caused by different frequencies

21 January 2018

interference pattern
The above photo (which I have colorized and cropped) from Wikimedia Commons illustrates how two similar wave patterns can interfere with each other.

I have been working with this basic phenomenon as a possible way to create interesting patterns in LED displays that could be configured to interact with the environment.

My simpler prototype uses 12 yellow LEDs in a circle. The illustrations below show them in rows. This made it much easier to draw the illustrations.

Two Signals

The basic idea is to compare two different signals in a way that is interesting.

This design uses voltage-controlled oscillators to create a pair of square waves.

Each wave is then applied to a circuit that turns it into a repeating pattern with twelve parts. The corresponding outputs are then compared, and an LED is turned on or off depending on the result of that comparison.

The comparison logic I used for my first prototype turns the LEDs on only when both outputs being compared are “on” (about +5 volts in this case). There are other types of logic possible. This particular one gives the lowest current usage from the power supply.

So there are 12 LEDs, and each LED can only be on for one-twelfth of the time it takes for the pattern to repeat. But they will all fully light during their time slot only if the two signals being compared are exactly the same.

Otherwise, the LEDs will turn on and off in a pattern based on how different the two signals are. Here I have illustrated a few possible patterns. The yellow strip is the “reference” frequency, and the light blue strip is the other frequency. The lime green bands depict which LEDs will turn on, and for how long, based on my chosen comparison logic.

If the two signals are close but not exactly the same, the circle of LEDs will dim and brighten as the signals slowly go in and out of alignment. This is similar to how two musical notes that are close to each other will “beat” (get louder and softer).

two similar frequencies

If the two signals are a lot different, but related mathematically, they will produce a pattern of light and dark in the display.

As it is almost impossible to adjust the two oscillators to exact frequency multiples, the actual result is a fast or slow rotation of the pattern, depending on how far off they are.

Oddly, a 3 times difference in frequency produces a 2-node pattern.

frequencies different by factor of three

And a 4 times difference in frequency produces a 3-node pattern.

frequencies different by factor of four

Here is an image of my prototype – doctored to remove most of the distracting details of wiring and so forth on the circuit boards – showing a 3-node pattern that is slowly rotating. Here, three LEDs are much brighter, and three others are just beginning to turn on as the pattern slowly rotates.

3 nodes in circle

Three node pattern with LEDs in a circle.

Other Designs

I also made a display that uses my “signature” pattern of 8 concentric circles, starting with one having only three LEDs in it, and ending with one that has ten LEDs. This is a more interesting display to watch, but the results are more difficult to interpret. It is also more difficult to make. So I will likely continue to work with simpler designs as I develop this idea.

Software

These designs don’t use any software; totally hard-wired, as they say. My experience with software that runs on controllers that I can afford is that it doesn’t run fast enough to provide a smooth display that doesn’t blink. So, though I plan to use controllers in some of these designs, I prefer designs where they are not needed and we are dealing totally with the real-time interactions of signals.